Ford 428 Engine Specs

Intro

➤ See the Family Page for specs common to all engines in this family.

The Ford 428 FE arrived for 1966 as the long-stroke heavyweight of the passenger-car FE family. It was not Ford trying to build another 427. That distinction matters. The 427 was the big-bore, shorter-stroke racing answer. The 428 used a smaller 4.130-inch bore and a longer 3.980-inch stroke to make strong torque where large street cars actually used it.

That made the original 428 perfectly at home in full-size Fords, Mercurys, Thunderbirds, police applications, and other machinery where effortless pull mattered more than what happened near the top of the tachometer. Four hundred twenty-eight cubic inches and nearly four inches of stroke will move a heavy car without needing a camshaft that makes the traffic lights nervous.

Then the Cobra Jet arrived and ruined everybody’s ability to discuss an ordinary 428 calmly.

The 428 Cobra Jet was the real thing. Ford took the long-stroke production engine, gave it better breathing and the supporting hardware for serious street and strip work, and put it into Mustangs, Cougars, Fairlanes, Torinos, Cyclones, and other muscle-era machinery. Suddenly the big-car torque engine had a performance reputation every later classified ad wanted to borrow.

That reputation is where the trouble begins. A standard 428, a Police Interceptor, a Cobra Jet, and a Super Cobra Jet are not four names for the same engine. They share displacement, but heads, induction, exhaust, camshaft, rotating hardware, balance details, application, and supporting equipment can change substantially.

The Super Cobra Jet needs an especially hard line around it. The SCJ was tied to Drag Pack applications and heavier-duty hardware intended to survive harder use. It was not created by adding a decal, a steep rear gear, or enough enthusiasm to the description. If somebody wants SCJ money, the engine and the car need to provide SCJ evidence.

The 428 also gets compared constantly with the 427 because the displacement numbers sit beside each other. Mechanically, they took different roads. The 427 got its cubes from a huge bore and retained the shorter FE performance stroke. The 428 got its cubes from more stroke. The 427 likes the racing story. The 428 makes its argument with torque.

That difference can make a 428 the better street engine. It does not need heroic rpm to make a heavy car move, and a sensible combination of compression, heads, camshaft, four-barrel induction, ignition, exhaust, and gearing can produce exactly the broad shove people expect from a big FE.

The long-stroke 428 also uses external balance, so the flywheel or flexplate and related rotating parts are not places to substitute ordinary 390 pieces because the bolt holes happen to agree. Super Cobra Jet rotating hardware adds another balance wrinkle. FE interchange gives you choices. It does not give you permission to stop thinking.

Today the 428 deserves attention whether or not it is a Cobra Jet. A correct standard engine belongs in plenty of important Ford and Mercury applications. A genuine Police Interceptor is interesting in its own right. A verified CJ or SCJ can be serious hardware and serious money.

Just do not let Cobra Jet fame promote every 428 in the parking lot.

Ford already built the good ones. Nobody needs to invent more.

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Overview

Ford introduced the 428 FE for 1966 as a production-friendly way to get more displacement and torque from the FE architecture without following the expensive racing path that produced the 427. The difference was fundamental. Instead of pushing bore diameter toward the limit, Ford used a 4.130-inch bore with a long 3.980-inch stroke.

That combination produced exactly the personality Ford needed. The engine made strong low- and midrange torque and fit naturally into heavy passenger cars, Thunderbirds, Mercurys, police applications, and other vehicles where broad power mattered more than sustained high-rpm competition use.

The basic architecture remained normal FE: 4.630-inch bore spacing, deep-skirt cast-iron block, five main bearings, in-block camshaft, front-mounted distributor, shaft-mounted rocker gear, and the large intake manifold extending beneath part of the valve-cover area. The 428 did not need exotic architecture to make torque. It mostly needed stroke.

Its 3.980-inch stroke was already familiar from the Mercury 410. The difference between those engines is bore. The 410 uses a 4.050-inch bore. The 428 enlarges it to 4.130 inches. Same long-stroke idea, another eighteen cubic inches.

That 4.130-inch bore also happens to match the earlier 406, which creates another useful comparison. The 406 uses approximately 3.785 inches of stroke and was developed as an early factory performance engine. The 428 stretches the crankshaft considerably farther. Same nominal bore. Entirely different character.

Then there is the 427 comparison everybody wants to make. The 427 uses a much larger bore of roughly 4.23 inches with the shorter 3.78-inch performance stroke. The 428 reverses the priorities with less bore and more stroke. That is why the two engines should not be treated as neighboring versions of the same idea simply because their names differ by one cubic inch.

The original 428 belonged mainly to the big-car torque side of Ford production. Full-size Ford, Mercury, and Thunderbird applications benefited from an engine that could move substantial weight smoothly without demanding high rpm. These early standard engines established the 428 before the Cobra Jet name existed.

Police Interceptor versions moved the engine toward heavier-duty service and performance without yet turning it into the later muscle-car combination. The PI therefore deserves its own identity. It was more serious than an ordinary luxury-car 428 but should not be retroactively promoted into a Cobra Jet because the later engine became more famous.

The major change came with the 428 Cobra Jet. Ford used the long-stroke 428 as the foundation for a stronger muscle-car package with improved breathing and supporting hardware. The result combined the production practicality and street torque of the 428 with enough airflow and performance equipment to make it a legitimate street-and-strip engine.

That combination was important because Ford did not have to use the expensive 427 as its normal muscle-car answer. The Cobra Jet could be installed in regular production performance cars in greater numbers while delivering exactly the kind of low- and midrange punch street tires, heavy cars, and quarter-mile racing could use.

The CJ’s factory reputation was well earned. It was also the beginning of sixty years of ordinary 428s being promoted by association. A Cobra Jet is a complete factory combination, not merely 428 cubic inches with a four-barrel carburetor.

Heads, intake, carburetor, exhaust manifolds, camshaft, distributor, compression, block and crank details, dates, application, and supporting equipment all contribute to a credible CJ claim. Some of those pieces can be changed in an afternoon. That is why one correct part proves one correct part.

The Super Cobra Jet pushed durability farther for Drag Pack use. The SCJ used heavier-duty rotating hardware, including stronger connecting rods, and required corresponding balance changes. Related Drag Pack equipment can also matter when verifying the original package.

That balance difference deserves more than collector attention. Standard 428s are externally balanced, and SCJ rotating hardware changes the balancing requirements further. Damper, flywheel or flexplate, crankshaft, rods, pistons, and any additional counterweighting need to be treated as one rotating system during a rebuild.

Mixing ordinary 390 balance pieces into a 428 because everything belongs to the FE family can create vibration even when everything bolts together. Mixing CJ and SCJ rotating pieces without knowing which balance scheme is being used can accomplish the same thing with more expensive parts.

For street use, the ordinary 428 recipe remains excellent. The displacement and stroke already provide torque, so the engine does not need excessive camshaft duration merely to prove somebody owns a parts catalog. Moderate compression, good cylinder heads, properly sized induction, useful exhaust, and sensible ignition timing can produce a broad, strong powerband.

The same displacement can also tolerate considerably more performance hardware when the rest of the combination supports it. Better heads and induction can wake up a 428 substantially because the engine has enough cubic inches to use airflow. But compression, camshaft, gearing, converter or clutch, vehicle weight, exhaust, and intended rpm still need to agree.

A big camshaft in a low-compression engine with tall gears remains a bad idea even when 428 is stamped on the air cleaner. Cubic inches forgive some mistakes. They do not issue pardons.

The normal FE intake-manifold problem remains part of any serious rebuild. Milling cylinder heads or decks can change manifold alignment, and poor fit can create vacuum leaks, oil leaks, coolant trouble, or port mismatch. The intake is too large and too integrated into the FE top end to be treated as an afterthought.

Identification deserves equal discipline because FE parts interchange so easily. A 390 can acquire a 428 crank. A 410 already shares the 428 stroke. Heads and intakes move between engines. Cobra Jet pieces can end up on standard blocks. Rebuilt engines can contain enough mixed parts that the current hardware and original identity are two different questions.

The bore-and-stroke measurements settle the mechanical displacement: 4.130 inches by 3.980 inches is the basic 428 combination. Proving that the engine was originally a standard 428, Police Interceptor, Cobra Jet, or Super Cobra Jet requires the rest of the evidence.

That distinction matters because value rises quickly with the famous names. A standard 428 can be a desirable engine. A genuine Cobra Jet can be worth considerably more. A real Super Cobra Jet with correct Drag Pack context can move the numbers again. As the price rises, “pretty sure” should be shown the door.

The 428 therefore occupies a unique place in the FE family. It was not born as Ford’s ultimate racing engine. It was born as a long-stroke production torque engine. Then Ford developed the Cobra Jet and Super Cobra Jet versions and discovered that the same qualities that made a big Thunderbird easy to move could make a muscle car extremely unpleasant to race against.

The 427 proved what the FE could do when racing wrote the specifications.

The 428 proved you could make a great street engine without asking the race department for permission.

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General Specs

Displacement	428 cid	Bore / Stroke	4.130″ x 3.980″
Production / Use Era	1966–1970 Ford FE passenger-car and performance era	Bore Spacing	4.630″
Engine Family	Ford FE big-block	Deck Height	10.170″
Block Material	Cast iron	Rod Length	6.488″
Cylinder Head Material	Cast iron	Main Journal	2.749″
Fuel / Induction	Gasoline; carbureted; 4-barrel, Police Interceptor, Cobra Jet, or Super Cobra Jet by version	Rod Journal	2.438″
Cam Location	Block-mounted cam	Main Bearings	5
Valve Layout	OHV, 2 valves per cylinder	Firing Order	1-5-4-2-6-3-7-8
Common Main Caps	2-bolt	Distributor Rotation	Counterclockwise
Rear Main Seal	2-piece	Weight	~625–650 lb complete iron FE
Balance	External balance; SCJ uses additional counterweighting with heavier Le Mans rods	Dimensions	~29H / ~27W / ~32L

Exact parts and specs can vary by year, vehicle, performance package, service history, and whether somebody already mixed FE parts without checking what actually fits. Use these numbers as the family baseline, then verify the actual block, crank, heads, induction, main-cap configuration, balance parts, and application before ordering parts or machining anything expensive.

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Variants

The 428 is where one displacement managed to collect four very different résumés. Ford started with a long-stroke passenger-car torque engine, toughened it for Police Interceptor duty, turned it into the Cobra Jet everybody remembers, and then gave the Super Cobra Jet heavier hardware for Drag Pack abuse. Same 4.130-inch bore and 3.980-inch stroke throughout. After that, the hardware decides which 428 is actually sitting on the stand.

Standard Passenger-Car 428

What it was: The original 428 was built to move heavy cars without making the driver chase rpm. Ford took the long 3.980-inch stroke, paired it with the 4.130-inch bore, and produced exactly the sort of broad torque a Thunderbird or full-size Ford could use without pretending the thing had entered NASCAR.

What changed: The standard 428 used conventional passenger-car FE heads, hydraulic camshaft, four-barrel induction, ordinary production exhaust, two-bolt mains, and the externally balanced long-stroke rotating assembly. It was a strong engine, but Ford did not give it the Cobra Jet’s complete breathing and performance package.

What that did: Nearly four inches of stroke put the emphasis exactly where a big street car needed it: low- and midrange torque. The engine did not have to wait for heroic rpm before the car started moving with authority. Four hundred twenty-eight cubic inches were already doing plenty of work before the tachometer became interesting.

Where used: Standard 428s appeared in full-size Fords, Mercurys, Thunderbirds, and other large passenger-car applications beginning in 1966.

Identification caution: Cobra Jet fame has spent decades leaking backward onto ordinary 428s. A four-barrel carburetor, performance intake, chrome air cleaner, or later CJ parts do not rewrite the engine’s birth certificate. Bore, stroke, heads, intake, exhaust, camshaft, dates, codes, and original application still need to agree.

428 Police Interceptor

What it was: The Police Interceptor was Ford making the 428 more serious without yet building the Cobra Jet. Police work required sustained speed, heavier-duty service, cooling, and performance that had to survive considerably longer than one quarter-mile trip.

What changed: Ford moved the PI away from the ordinary luxury-car combination with more performance-oriented induction, heads, exhaust, camshaft and calibration, along with the supporting heavy-duty equipment required for law-enforcement service.

What that did: The PI retained the 428’s broad torque but gave it more breathing and harder-duty capability. That made it a useful bridge between the regular passenger engine and the later Cobra Jet. The Geezer would advise leaving it there instead of promoting every PI into a CJ because the later engine got better press.

Where used: Police Interceptor 428s appeared in Ford law-enforcement and heavy-duty service applications before and alongside the rise of the Cobra Jet.

Identification caution: Police Interceptor is not another word for Cobra Jet. A genuine PI claim needs the right application, induction, exhaust, camshaft, compression, codes, dates, and supporting hardware. A siren bracket does not identify the engine any more than fuzzy dice identify the rear axle.

428 Cobra Jet

What it was: This is where the 428 stopped being merely a very good big-car engine and became one of Ford’s defining muscle-era combinations. Ford kept the long-stroke torque foundation and gave it the breathing hardware needed to make that torque useful farther up the tach.

What changed: The Cobra Jet used performance-oriented cylinder heads, four-barrel induction, improved intake and exhaust hardware, hotter camshaft and ignition calibration, and supporting pieces aimed at serious street and strip use. The basic 428 remained externally balanced and retained the long-stroke character that separated it from the big-bore, shorter-stroke 427.

What that did: The CJ combined the ordinary 428’s heavy-fisted low-speed pull with much better airflow. That is why it worked so well in muscle cars. It did not need 7,000 rpm and racing manners to be quick. It simply made a lot of torque, kept breathing, and asked the tires whether they had made any long-term plans.

Where used: Cobra Jet 428s appeared in Mustangs, Cougars, Fairlanes, Torinos, Cyclones, and related Ford and Mercury performance applications.

Identification caution: Cobra Jet parts move easily between FE engines. Heads, intake, carburetor, exhaust manifolds, distributor, air-cleaner hardware, and valve covers can all be installed later. One correct part proves one correct part. A genuine CJ claim needs the block, rotating assembly, heads, induction, exhaust, codes, dates, application, and documentation to tell the same story.

428 Super Cobra Jet — Drag Pack

What it was: The Super Cobra Jet was not Ford discovering five more horsepower under another decal. It was the Cobra Jet strengthened for the sort of Drag Pack use that makes ordinary rotating assemblies reconsider their career choices.

What changed: Ford added heavier-duty rotating hardware, including stronger Le Mans-type connecting rods, with corresponding changes to the balance system. The SCJ therefore used additional counterweighting beyond the standard externally balanced 428 arrangement. Drag Pack equipment and oil-cooler hardware also became part of the proper package context.

What that did: The important gain was durability, not a dramatic brochure horsepower increase. Deeper gearing, better traction, repeated hard launches, and sustained rpm put loads into the rods and crank that an ordinary street engine could happily avoid. Ford strengthened the pieces that had to stay inside the block when the driver stopped being polite.

Where used: The 428 SCJ belonged to Drag Pack-equipped Ford and Mercury performance applications where harder drag-oriented use justified the stronger rotating assembly and related equipment.

Identification caution: This is where the wallet needs both eyes open. A real SCJ claim needs the correct rods, crank and balance arrangement, Drag Pack context, oil-cooler equipment where applicable, axle/package evidence, codes, dates, and supporting hardware. A CJ with steep gears is not automatically an SCJ, and a loose engine on a stand may not contain enough evidence to prove the claim at all.

The 428 story is simple once the famous names quit shouting over each other. The standard engine was Ford’s long-stroke torque piece. The Police Interceptor made it tougher. The Cobra Jet gave it the airflow and muscle-car hardware that built the reputation. The Super Cobra Jet strengthened the rotating assembly for harder drag use. Same cubic inches. Four different jobs. On a 428, the decal starts the argument. The parts finish it.

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Key Notes

The 428 FE is where Ford FE stories sound simple right up until the money shows up. People hear “428” and jump straight to Cobra Jet, Mustang, drag-strip glory, and big torque. Some of that is real. A lot of it is seller perfume. A 428 can be a plain passenger-car torque engine, a Police Interceptor-style engine, a Cobra Jet, a Super Cobra Jet, a Mercury performance engine, or a mixed FE wearing the right number and the wrong parts.

The bore and stroke explain the 428’s personality. With a 4.130-inch bore and 3.980-inch stroke, the 428 used a smaller bore and longer stroke than the 427, which gave it a different job. The 427 was the sharper racing answer. The 428 was the street-torque bruiser. It pulled hard where heavy cars and street tires actually lived, which is why it became so useful in muscle-era Ford and Mercury packages.

The 428 is not automatically a Cobra Jet. That mistake has probably paid for more fake parts than anyone wants to admit. Ford built regular 428s, police-style versions, Thunderbird and full-size versions, Mercury versions, Cobra Jets, Super Cobra Jets, and plenty of engines that got rebuilt, swapped, and dressed up later. Same displacement does not prove the heads, intake, carburetor, exhaust manifolds, camshaft, crankshaft, rods, block details, date codes, or vehicle application.

Cobra Jet claims need paperwork, parts, and patience. The 428 Cobra Jet was real, serious, and valuable, but a plain 428 with a four-barrel and confidence does not become one. Block details, heads, intake, carburetor, exhaust manifolds, camshaft, crankshaft, rods, distributor, date codes, vehicle context, and documentation all need to agree. A shaker scoop, chrome air cleaner, or loud idle can support a story. It doesn’t prove the birth certificate.

Super Cobra Jet claims need an even harder look. The SCJ label brings specific drag-pack context, heavier-duty rotating parts, balancing differences, oil-cooler-related equipment in the right applications, and bigger money. A seller doesn’t get to say “SCJ” because the car has gears and attitude. If the claim adds dollars, the parts and paperwork need to add proof.

The 428 and 427 get confused by people who think the bigger number must mean the bigger legend. Wrong game. The 428 has the longer stroke and street torque. The 427 has the larger bore, shorter stroke, racing block reputation, and side-oiler mythology when the claim is right. Both can be valuable. Neither one becomes the other because somebody wants the better story on the invoice.

The 428 also gets tangled with 390 and 410 stories. A stroked 390, a Mercury 410, a dressed-up FE, or a pile of family parts does not become a real 428 because the air cleaner says something exciting. Bore, stroke, crankshaft, pistons, block casting, heads, intake, carburetion, date context, and vehicle application all need checking. The crank and bore do not care what the decal says.

Factory horsepower numbers need a leash. The 428 lived in the gross-horsepower era, and Cobra Jet ratings were famously conservative or at least suspiciously polite for what the engines could do. The numbers are useful as period labels, but they are not the whole story. Hardware, application, gearing, traction, and proof usually say more than the brochure.

Heads, exhaust, and induction matter because the 428 was built around torque, not fairy dust. The right CJ-style parts can make a real difference. The wrong heads, wrong manifolds, lazy compression, too much camshaft, weak exhaust, or mismatched carburetion can turn a strong FE into a big expensive cough. The 428 has grunt, but grunt still needs a decent path out of the engine.

FE interchange helps, but the 428 is not where casual parts mixing belongs. Intakes, heads, exhaust manifolds, front dress, water pump, distributor, pulleys, flywheel or flexplate, damper, crankshaft, rods, and application-specific pieces can vary by year and version. Some parts fit. Some parts fit and ruin the claim. Some parts fit and make the engine worse. “It’s an FE” is the beginning of the question, not the answer.

Factory specs and current hardware can be miles apart. Many 428s and claimed 428s have been rebuilt, swapped, re-cammed, re-headed, re-carbureted, overbored, dressed as Cobra Jets, mixed with 390 or 410 parts, or advertised by people who know the number wakes buyers up. The engine in front of you tells the current story. Casting numbers, date codes, bore, stroke, crankshaft, heads, pistons, intake, carburetor, distributor, front dress, and vehicle context all need checking.

The 428’s value follows proof, version, and application, not the loudest decal in the room. A regular 428 can be useful and valuable. A correct 428 in the right Thunderbird, full-size Ford, Mercury, Mustang, Torino, Cougar, or Cyclone context can be better. A documented Cobra Jet or Super Cobra Jet is a different level of money. A loose FE with a story is just a bill waiting for a flashlight and a measuring tool.

The 428 earned its reputation because it made big street torque and gave Ford a serious muscle-era answer without needing the race-only sharpness of the 427. It doesn’t need fake Cobra Jet claims, borrowed side-oiler shine, SCJ fog, or 390 stroker confusion to be worth owning. Verify the bore and stroke, prove the version, match the parts, and price the engine by evidence instead of letting the badge do all the talking.

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Bottom Line

The Ford 428 FE is the long-stroke torque bruiser of the family, and that is enough of a reputation without pretending every one came with a Cobra Jet halo. Ford gave it the kind of low-end and midrange shove that makes a heavy car feel considerably less heavy, then the Cobra Jet and Super Cobra Jet versions added enough muscle-era glory to make buyers start hearing trumpets whenever somebody says “428.”

That is where judgment needs to stay awake. A plain 428, a Police Interceptor, a Cobra Jet, and a Super Cobra Jet are not four ways of describing the same engine. Same displacement does not prove the heads, induction, exhaust, balance parts, application, dates, or performance package. The famous versions earned their names. The ordinary ones do not get promoted by association.

The good part is that even a regular 428 has a legitimate reason to exist. The long stroke gives it serious street torque without asking for the 427’s more specialized racing hardware or high-rpm personality. In the right Ford, Mercury, Mustang, Cougar, Torino, Shelby application, or full-size cruiser, a properly built 428 can deliver the sort of heavy-fisted throttle response that makes dyno-sheet speeches unnecessary.

But this is still an engine where boring questions save expensive mistakes. Check the block, crankshaft, balance setup, heads, intake, carburetion, exhaust manifolds, dates, application, and actual condition. A missing balance piece or a seller who suddenly gets vague when the flashlight comes out is not part of the Cobra Jet mystique. It is a warning.

So buy the 428 for verified torque, correct hardware, and the right application. The 390 is easier to own, and the 427 carries the harder racing pedigree. The 428 is the street hammer in between. Some are genuinely special. Some are simply big and useful. Both deserve respect. Only the proven ones deserve the price tag standing at attention.

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